The present invention relates to material handling vehicles, and more particularly to a material handling vehicle with multiple control handles for operation in a variety of operator orientations.
Material handling vehicles commonly found in warehouse and factory environments include, for example, vehicles in which the operator normally stands on a platform at the rear of the truck, at the end opposite of a load carrying or load handling mechanism, typically employing forks to lift and transport material. To provide an efficient flow of goods in such facilities, operators of these vehicles typically orient their bodies in the most comfortable position for adequate visibility to drive the material handling vehicles in both a forks first direction, with the vehicle forks leading in the direction of travel, and tractor first direction, in which the vehicle forks trail in the direction of travel.
Although in a typical vehicle there are a variety of possible operator orientations, when traveling, an operator will favor positions that maximize comfort and visibility for forks first and tractor first travel. Generally, one operator orientation is used more frequently than the others. The prevalent orientation varies with vehicle design, from facility to facility, within a given facility, and even from operator to operator. There is, therefore, a fundamental need to provide stability to the operator when traveling for all likely orientations, while maintaining operator comfort and the maximum productivity potential of the vehicle.
For these reasons, designers of lift trucks have developed a number of different operator compartment configurations. Available configurations include both standing and seated configurations in which the operator faces either generally to one side or to the front/rear of the truck. Vehicles designed for a standing operator (stand-up vehicles), include both side stance configurations where the operator generally operates the truck when standing facing the left side of the truck and, fore/aft configurations in which the operator may either stand facing the load or away from the load. For each of these configurations, designers have further provided various methods to accommodate operator stability for travel in both the forks first and tractor first directions, and to provide each design with a reasonable degree of comfort for the operator, while ensuring the capability for vehicle productivity. Stand-up vehicle designs, for example, typically impart stability, in part, through hand operated vehicle controls that provide both stability and the means to control the operation of the vehicle. Operator stability when traveling is accomplished through a combination of solid footing, pads and covers that embrace portions of the operators body, hands on the vehicle controls and an operator advanced knowledge of the commanded vehicle motions.
Typical prior art stand-up vehicles utilize the same control elements to command travel in either direction and for either stance orientation. That is, the truck operator manipulates the same steering device, travel control, and deadman foot control regardless of stance orientation. In the case of stand-up trucks configured in the fore/aft sense, although designed to be intuitive for bi-directional control, some operators nonetheless find the controls more convenient for forks first travel than for tractor first travel. Furthermore, these controls often do not provide maximum comfort for the widest possible range of operator sizes, as the operator must reach beside and slightly rearward of his or her centerline in order to control the vehicle travel speed when facing in the tractor first direction.